Artificial ankle joint



ARTIFICIAL ANKLE JOINT Filed Feb. 5. 19:50

3nnentor.

Fatentecl Aug. 23, 1932 MILO E. men, or KANsAsorT'Y, vrrssounrj RTIFICIAL ANKLE iroiittr 7' i Application filed February 3, 1 30. serial;lto. 425,534.

This invention relates to ankle joints for artificial legs, and has for its general object to produce a construction which willallow the leg to assume an angle with regard to the foot, in a plane at an angle transverse to the plane of the longitudinal center of the foot, as, for example, when the wearer of the leg places the foot on a side hill or surface eX- tending transversely of the length of the foot.

As far as I am aware no one has yet produced an ankle joint which was commercial- 1y successful in accommodating a large angle of variation as above recited without danger of the joint becoming separated and leading to the fall of the wearer. In certain other types of construction the swinging or rocking of the leg with respect to the foot is restricted to a plane parallel to a plane passing through the longitudinal center of the foot with no accommodation to meet transverse inclination as mentioned. With this type of leg the wearer is subjected to side strain or injury to the stump when he places the foot on a side hill orsimilar inclined surface. 7

A further object of the invention is to produce an artificial ankle joint which is of strong, durable, etficient, simple. and light construction having a minimum of operating parts and which will be substantially noiseless in use and will cushion the vibration, shock or jar so that it is greatly diminished before it reaches the wearer of the leg.

lVith the general objects named in view and others as will. hereinafter appear, the invention consists in certain novel and useful features of construction and organization of parts as hereinafter described and claimed; and in order that it may be fully understood, reference is to be had to the accompanying drawing, in which:

Figure 1 is a central vertical section through an artificial ankle joint embodying the invention.

Figure 2 is a section on the line IIII of Figure 1 with part of the leg in elevation and with the resilient sleeve omitted.

Figure 3 is a section through the locking or retaining bar for the heel cord which i5 usedto limit-the for-ward rocking movement of theileg on the ankle' joint..i a J V. Figure 4 is a perspective view'ofxa slightly modified form of ball joint.

Infthe said drawing, where like reference 55 characters identify corresponding parts in all ofrthe figures,*1-.indicates an artificialleg which is jpreferably hollow "as illustrated. The lower end of the leg is reduced as-at '2,

and said reduced portion, in a plane extend- 6d ing longitudinally of the foot,- is bifurcated and terminates in a pair ofi semi-spherical shaped ends or balls 3 and 4. V i

The ends 3 and 4 in the preferred constructioir areprovided with individual me'-' talliecaps or balls '5. In the modified coristruction shown in'Figure 4, the ball joints are:=castintegrally as at 6 and are provided with a. pair iofiipward ly, extending straps 8 to :be fastenedtothe reduced end 2 of. the

leg. i I j The foot 9 ofthe invention is provided with a pair of semi-spherical sockets 1.0 and 11*,spaced equal distances on opposite sides of the longitudinal center line: of the foot.

The sockets '10 and 11 arepreferably lined with leather 12' or other cushioning and sound-deadening and wear res'isting material whichpreferably is made of a single piece andprovides an abutment wall 13 between the two sockets.

Referringto Figurel, it" willbe evident that the leg can'rock back and forthlin a plane parallel to the 'length of the foot on the balls 5 inthe' sockets 10 land 11,-the-forward' 3 5' movement being liniitedby heel cord .14 se-' cured at onerend in argroove 15 formed in therearfend of heel of the foot 9 and extending upwardly through the reduced portion 2 of the leg and having its upper end secured to a cross pin 16 carriedby the leg as illustrated. The foot and leg are fitted in a resilient sleeve joint 17 which deadens the sound and cushions the jar incident to walking and binds the parts together. 9

l Vhenthe wearer of a leg equipped with an ankle joint as described, steps on asurface inclined-transversely of the length of the foot '(see Figure 2), itis possible for the/parts to rock on one of the ball and 109 socket joints as illustrated, and if the angle is extreme, the other ball may move com-- pletely out of its respective socket. It will be evident that with the construction described and illustrated there is not the remotest possibility that the joint will slip out of the socket and permitthe wearerlto fall as thessupporting area of the. ballf'andcsocket is always practically constant regardless of the angle formed between the foot :and the leg; The foot cannot become'detachedfrom the anklenor the balls 'disengagedfromtheir sockets, as the foot is bound to the leg by a resilient rubber or othensuitablecovering 17 as common in the art. After the foot has rocked as described ,theoresiliency of the cover and the gr'avitative;weightyofitherfoot will ialw a'ys cause it .to return to normal. position.

F row. the" above; descriptiomgit s ,Wilklbe apparentthatl haveproducedja; constructionwhich embodies all. of: the :features'of a-dvana-i tagecset forth. :as..desirable ,l and while Ifhave described and claimed; the; preferred: embodi merit of thesame; it is to .be: understoodwthat I reserve the right to .make allzchanges :pere

missible lover-theprior art: 1

I I claim:

1. In an artificialleg structure, afoot portion hav ingan ankle-ljointcplate consistingv of; two. integral laterally alinedmsockets occupying: planes atopposite sides-#ofithe. I

' longitudinal icenter: of:v the foot portionpand:

a pairof arms rigidywith. and projecting upward from theisocketseatttheyouter sides and midway the length thereof. 7

2. In; anaarti-ficiaLleg astructure,:a leg portion havinga depending shank provided with laterally-spaced. depending semisspherical portions, a foot portionhaiving: apair: ofv laterally-spaced, semisphericzil sockets re:- ceiving' said: pair offsemi-spherical portions to constitute independent. fu-lcrumsa upon; either "of which: therfOOt PO-ItlOIlyiCfiIIxtll-t' laterally relative to the leg port'iorgto;per

mit the other semi-sphericalportion-rand" socket: to: separate, and; ana elastic shoe-com- V pletely encasing andftightly fitting the foot and shankiportions and bearingat its. upper edge firinly against: the lower: end of thealeg portionzaround'the shank. z

V In testimeny whereof I aflixqnyt-signature;

MIIJO RICE- 

